Dipeptidyl peptidase IV (DP IV) is a serine protease which cleaves N-terminal dipeptides from a peptide chain containing, preferably, a proline residue in the penultimate position. Although the biological role of DP IV in mammalian systems has not been completely established, it is believed to play an important role in neuropeptide metabolism, T-cell activation, attachment of cancer cells to the endothelium and the entry of HIV into lymphoid cells.
DP IV is responsible for inactivating glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide also known as gastric-inhibitory peptide (GIP). GLP-1 is a major stimulator of pancreatic insulin secretion and has direct beneficial effects on glucose disposal. Inhibition of DP IV and DP IV-like enzyme activity has been shown to represent an attractive approach e.g. for treating type 2 diabetes (also: non-insulin-dependent diabetes mellitus or NIDDM), see WO97/40832 and U.S. Pat. No. 6,303,661.
There are a broad variety of DP IV-inhibitors known in the state of the art, and the mechanism of action of these DP IV-inhibitors is mainly by competitive inhibition. WO99/61431 discloses competitive DP IV-inhibitors comprising an amino acid residue and a thiazolidine or pyrrolidine group, and salts thereof, especially L-threo-isoleucyl thiazolidine, L-allo-isoleucyl thiazolidine, L-threo-isoleucyl pyrrolidine, L-allo-isoleucyl pyrrolidine, and salts thereof. WO03/002593 discloses peptide structures useful for competitive modulation of DP IV-activity.
WO95/29691 discloses peptidyl derivatives of diesters of alpha-aminoalkylphosphonic acids, their use in inhibiting serine proteases with chymotrypsin-like, trypsin-like, elastase-like, and dipeptidyl peptidase IV specificity, and their roles as anti-inflammatory agents, anticoagulants, anti-tumor agents, and anti-AIDS agents.
WO99/38501 discloses DP IV-inhibitors which comprise a boronic acid or a phosphorylalkyl residue, and a method of regulating glucose metabolism by administering these compounds to an animal. WO99/38501 does not disclose compounds comprising a cyclopropyl-fused proline mimetic.
WO01/68603 discloses cyclopropyl-fused pyrrolidine-based inhibitors of dipeptidyl peptidase IV and a method of treating diabetes, especially type II diabetes, employing such cyclopropyl-fused pyrrolidines. WO11/68603 does not disclose compounds comprising a boronic acid or a phosphonic acid ester moiety as substituent on the pyrrolidine group.
WO2005/047297 discloses certain heterocyclic boronic acid compounds said to be inhibitors of dipeptidyl peptidase IV.